<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>



<script>
    let arr=[1,'2',"abc",' '];
    console.log(arr.length);

    arr[5]=null;
    console.log(arr.length);


    for (let a of arr) {
        console.log(a);
    }

</script>
</html>